Introduction to Human and Computer Capabilities

Why do we need to study this chapter?

To understand the interaction between humans and computers, we need to understand the limitations and capabilities of both. Before we design something for humans, we need to know the things humans find difficult or easy to perform and understand. We also need to be aware of the constraints of the system and the functionality available in it.

In this chapter, we first take a look at how humans perceive external stimuli. We then talk about how human memory works, followed by a discussion on our thinking and problem-solving abilities.

Later in this chapter, we look into the input and output channels of a computer. Then we learn about the limitations of computer memory, such as storage capacity and computational power because we don’t want to design an interface that is beyond a computer’s processing capability.

The human

In order to design an interface that meets the users’ requirements and meshes well with their habits, we first need to understand how people perceive things, remember, learn, and think. All these capabilities come under the umbrella of cognitive psychology.

Note: Cognitive psychology is the study of mental processes including thinking, learning, memory, perception, language use, attention, and problem-solving.

Model human processor

Model human processor is a cognitive psychology model developed by Card, Moran, and Newell in 1983. The model has three subsystems:

• Perceptual system: Organs like eyes and ears deal with the sensory stimuli, received as input, from the outside world.
• Cognitive system: This system deals with the processing required on the input to understand what is happening and what needs to be done.
• Motor system: This system handles the actions you perform after processing information.

A very basic model of a human acting as an information processor can be represented as follows:

Feeling overwhelmed due to so many unknown terms? Don’t worry, the next few lessons will cover each of the important points of this model.

Human input-output channels

Human input channels are mainly their senses, and their output channels are their effectorsEffectors are body parts such as muscles that are capable of producing a response to detected stimuli.. Here are the lists of both input and output channels:

Among all senses, the first three, vision, hearing, and touch, are primarily important in HCI. While using a computer, a seeing user receives information from the screen through sight, and the computer interacts with the user by making sounds indicating success, warning, or failure. While typing, the user feels the keys pressing, using their sense of touch to know what is happening. The other two senses do not currently play a significant role in interacting with computing devices.

Among all effectors, fingers play the most significant role in HCI. Fingers interact with a keyboard and mouse to give input to the computer. Voice recognition devices such as Siri and Alexa control devices using the human voice. Stephen Hawking, a physicist and cosmologist who had a motor neuron disease, designed systems that he could control with his eyes, eyebrow movement, and cheek movement.

Other effectors are used in the fields of virtual and augmented reality to give inputs to the computer system. For example, Npointer is an application that allows users to control the system with their voice and gestures. Hand movements are detected and recorded by webcam and translated to mouse and trackpad movements. Also, a person with a disability can control the system through head movements.

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